Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Avalanche highlights from Monday included a large natural avalanche that ran from additional wind-loading and a couple human triggered avalanches that were remotely triggered. (1&2). You can enjoy this beautiful weather and recent snow, but need to do so through your terrain selection. Choosing lower-angled terrain and smaller terrain features with lower potential consequences are two techniques you can use to reduce your exposure to the avalanche problems. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2.5

    2 to 3 feet of snow accumulated last weekend over persistent weak layers. With each passing day of mild weather, this avalanche problem will become less sensitive to human triggering, but the potential large and deadly size will not change. This avalanche problem may also give fewer warnings and obvious signs of instability. The most concerning aspects are northerly and easterly-facing slopes. Potential outliers exist in more isolated terrain features on other aspects. These avalanches have the potential to break wider than you expect, and they can be triggered from flat slopes connected to steeper terrain. Consider the consequences of a large avalanche in the terrain you want to ride, smaller terrain features can lower that consequence. While lower slope angles, without overhead hazards, can lower the chance of triggering an avalanche. 

    12/4:   A large persistent slab (D2.5) that ran from wind-loading Monday afternoon in the Martini.  

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Yesterday, northerly winds at 12,000ft averaged 20 to 30mph with gusts around 50mph. Those winds were transporting snow, though not very effectively. If you are riding southerly facing terrain, keep an eye out for wind-loaded terrain features and keep this potential avalanche problem in mind. Today's warm temperatures may temporarily make this avalanche problem more reactive as those higher-elevation slabs soften.  

    An example of recent wind-loading. Notice the fat-looking pillow in the red circle and the wind-eroded slope to the right. 

Avalanche Discussion

Avalanche highlights from Monday included a large natural avalanche that ran from additional wind-loading and a couple human triggered avalanches that were remotely triggered. (1&2). Some observers further reported obvious signs to instability while others didn't experience those same red flags. Those warning signs can make decision-making easier, but experiencing a lack of those warning signs can make it harder to stay mindful of the potential avalanche problem if you are traveling in suspect terrain. With each passing day of mild weather, we can expect fewer warning signs and a slow decrease in the likelihood of triggering the persistent slab avalanche problem. Despite how reactive things are, the snowpack structure isn't trustworthy. Stay mindful of your terrain selection and the consequences of the avalanche problem over these next couple of days of beautiful weather. 

We have recorded three notable avalanche cycles this season, with the most recent occurring last weekend. The underlying problem has been the same through all three cycles. Weak faceted snow exits near the bottom of the snowpack, primarily on northerly to easterly facing slopes, and each time a storm loads those weak layers the persistent slab avalanche problem reactivates. There is a lot of recent avalanche data in the observations tab. You can use the filters to further find the specifics you may be looking for in that data. In summary of last weekend's avalanche cycle, there have been 104 avalanches recorded so far across our entire forecast area. Those avalanches were made up of both persistent slabs and storm-related avalanche problems. The storm-related avalanche problems are fading out, while the persistent slab avalanche problem will be with us for some time. Those persistent slab avalanches were concentrated to NW to N to E aspects at all elevations, with a few outliers or unknowns on southeast and west aspects. Some avalanches have come close to a D3, but so far the largest avalanche size recorded have been D2.5's.

Events:  Thank you to everyone who attended our Avalanche Awareness Night and Beacon Brushup last weekend!  We are hosting our annual Christmas Tree Sale this Friday-Sunday.  Look for us at Ace Hardware from noon til 7 pm. 

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